1. Technical Field
The present invention relates to a printed circuit board.
2. Related Art
In recent years, unwanted radiation of electromagnetic waves (electromagnetic radiation) has become a problem in various kinds of electronic equipment. It has been known that electromagnetic radiation is chiefly caused not by a signal line but a power source system, that is, caused by electric resonance between a power source layer and a ground layer in a printed circuit board. For example, when a multi-layer printed circuit board has a power source layer and a ground layer which are quadrilateral, the printed circuit board serves as a parallel plate resonator to generate a natural resonance frequency (standing wave) between the power source layer and the ground layer.